This invention relates to a hairdressing apparatus which is available to supply adequate moisture to the hair of the head or the face by spraying steam thereupon in order to facilitate the beauty treatment of producing permanent waves, curling hair or shaving faces at barber shops or beauty salons.
A steam hairdressing apparatus as shown in FIG. 3 and FIG. 4 is already known as an apparatus for spraying steam upon hairs of a person in hairdressing treatments. The steam hairdressing apparatus 100 comprises a main body 102 supported on a stand pole (not shown in FIG. 4) and a dome 104 mounted on the main body 102 permitting slight raising or lowering.
The main body 102 has an evaporator 106 therein. An U-shaped spouting tube 108 is equipped inside the dome 104. An exit 110 of the evaporator 106 is connected with a middle point of the U-shaped spouting tube 108 by a flexible communicating tube 112. A plurality of narrow gushing holes 114 are perforated on the spouting tube 108.
The evaporator 106 is usually safely positioned lower than the spouting tube 108. It consists of a closed-type tank 116 for containing water therein and an electric heater 118 fixed in the tank 116.
The electric heater 118 boils and evaporates the water in the tank 116. The hot steam generated by the electric heater 118 ascends through the slant communicating tube 112. Then the hot steam spouts from the gushing holes 114 into the dome 104. The temperature of the steam is nearly 100.degree. C. at the moment of gushing. Cool external air also flows into the dome 104 through a narrow gap between the lower edge of the dome and the head inserted therein. The hot steam and the cool air mix in the dome. If the mixing condition is best, the temperature of the mixed gas becomes 50.degree. C.-60.degree. C. Such a gas is adequate to moisten the hair of the head effectively without danger.
The conventional hairdressing apparatus has some inconveniences.
Because the steam is spouted from the gushing holes 114 by action of the vapor pressure itself, the temperature of the water contained in the tank 116 must always be kept nearly at the boiling point of water--about 100.degree. C. under an ordinary atmospheric pressure. As is well known, the pressure of mixed gases is equal to the sum of the partical pressures of the individual gases. In the closed-type tank 116 exists only aqueous vapour, because no other kind of gas ever flows into the tank 116. The dome 104 is under atmospheric pressure. In order that gas may spout outward into the dome, the pressure in the tank 116 must be higher than the atmospheric pressure. Therefore the temperature must be kept more than 100.degree. C. in the tank 116.
Then the temperature of the aqueous vapor spouting through the gushing holes 114 is still nearly 100.degree. C. It is dangerous that such hot steam is sprayed directly upon the head of a person receiving hairdressing treatment. Though the gushing holes 114 are upwardly directed to increase the chance of mixing steam with cool air, it may be insufficient for creating a full mixture.
Occasionally abrupt boiling phenomena happens in the evaporator 106, when it is overheated more than 100.degree. C. The phenomena is dangerous. It may cause an accidental burn on a head, because hot water--not vapor--of about 100.degree. C. spouts from the gushing holes 114.
Furthermore in the conventional steam hairdressing apparatus, the temperature and the flow of the steam is poorly controllable. The adjustment of the temperature or the flow must be done only by changing the electric power supplied to the electric heater 118. Such a control is very uncertain and inaccurate, because it is indirect and accompanied by a large time lag and large hysterisis.
Finally the work of perforating many narrow gushing holes 114 on the spouting tube 108 is a very tedious process. It lowers productivity and pushes up the cost. Besides, the narrow gushing holes 114 cause a large pressure loss in the flow of steam.